There are a class of games called board games including, in particular, games such as checkers, chess, Go, backgammon, monopoly, shogi, etc., whose play involves the use of a flat game board, suitably marked, and of playing pieces, men, counters, etc., which are placed on the game board and whose positions on the board indicate the condition and progress of the game. There are a number of such games, which, if played seriously, are likely to require more time than may be available in a single session. Notable among these are chess and Go. If a game is adjourned before completion, to be completed at a later time, it is necessary to assure that the positions of the pieces on the board can be preserved in the interim or accurately restored when the game is resumed.
In chess, it is easy to record a position--either graphically or using Forsyth notation--and to set up the same position at the start of a subsequent session. Moreover, there are magnetic and peg-in chess sets, which are fairly satisfactory to use, and which retain a position between playing sessions reasonably securely. A retainer for chess, analogous to the invention disclosed herein, could be constructed in the form of a thin flat rigid sheet of suitable material joined to (or fabricated integrally with) a set of nine vertical and nine horizontal partitions intersecting to provide an array of sixty-four cells of square cross section, corresponding to the sixty-four squares of the chess board, the cells being of a depth sufficient to accommodate the kings (and hence, any of the men) and the array being placed over the chess board and held in place with clips or other retention devices. Such a retainer is one of the features of Goldsmith, U.S. Pat. No. 2,511,774, where it is used, apparently, in combination with chess men specially modified to be much shorter than normal and of uniform height. A similar retainer for use with chess men of normal design would be bulky and awkward to use and to store when not in use, and since, as noted above, it is not much needed, it would probably achieve very little acceptance in the marketplace.
With Go, however, the situation is very different. An understanding of this difference and of the usefulness of this invention requires some knowledge of the game and of the equipment with which it is played. Go is a game of strategy and tactics, with no inherent element of chance, played between two players. A Go board is rectangular, its width being approximately nine-tenths of its length, so that from the perspective of the players looking down at it, it appears to be approximately square. It is of uniform background color and is marked with nineteen evenly spaced vertical lines intersected by nineteen evenly spaced horizontal lines, so that there are three hundred and sixty-one points of intersection, including those along the outer edges. The playing pieces, called "stones", are all of the same shape and nearly the same size and are of two colors--black for one player and white for the other. They are disc-like, having, for use on a standard sized playing board, a diameter of about 22 millimeters and a thickness at the center of from 6 to 10 millimeters, each increase of a millimeter in thickness corresponding to a very significant increase in the cost of a set of stones. Both top and bottom surfaces are convex, so they are much thinner at the outer circumference than at the center. They are ordinarily kept in bowls, from which the players withdraw them one at a time to be played down onto the board. The covers of the bowls may be inverted and used to hold any stones of the opposite color which are captured in the course of the game.
At the start of a game, the board is empty (unless a small number of handicap stones are placed in prescribed positions for the benefit of the weaker of the two players) and the players alternate in placing stones of their own color onto the board--placing them not in the rectangles formed by the intersecting lines but on the points of intersection. A stone, once placed, is not moved until the end of the game, unless it is captured. With good play on both sides, relatively few stones will be captured, so if a game is adjourned to be completed later, there may well be over two hundred stones on the board. Obviously, it would be impractical to record the position and clear the board, since setting up the position again for a subsequent session, with due care to replace each stone in its correct position, might well take more time than had been spent in playing the stones originally.
Magnetic Go sets have been manufactured and sold, but they are not very satisfactory. At the end of a game, the stones are rearranged so that the territories surrounded and controlled by the two players are reshaped into rectangular areas for easy counting; magnetic stones tend to interact in unpredictable ways when this is done. They also cling to each other in the bowl from which they are taken in play and this makes the handling of them awkward and unpleasing.
The game could be played with pencil and paper, or with felt "stones" on a felt board, but to most Go players such means of play would be altogether unsatisfactory. The size and shape of the board and stones and the materials from which they are made are a part of a tradition established through thousands of years of play. Go is an integral part of the culture of the societies in which it is played; verbal expressions relating to the game are used metaphorically in ordinary conversation, even by non-players. A familiar feature of the game is the sound of its being played--unlike chess where the men have felt-covered bases and the play is expected to be entirely silent. The best Go boards are hollowed out underneath to impart a resonance to the cheerful click of the stones as they are placed down onto the board with characteristic vigor. An acceptable retainer will not require modifying the appearance or the nature of the stones or of the playing surface.
Another feature of the game is related to a general antipathy to exact symmetry. The stones are usually placed on the board without any effort to locate them precisely over an intersection and, since the diameter of the stones is slightly greater than the spacing of the vertical lines on the board, a horizontal line of adjacent stones must necessarily overlap a bit. Hence, an acceptable retainer for Go cannot use a structure with solid vertical and horizontal intersecting partitions dividing the playing space into three hundred and sixty-one entirely separate cells. When a retainer is placed over the board, it will be acceptable if the stone, are nudged slightly toward being better centered over their intersections, but preferably their positions should not be too severely regularized and it is essential that adjacent stones be permitted to overlap slightly. It is highly desirable for the top surface of the retainer to be transparent, so that both players can observe that no stones are inadvertently shifted to different positions as the retainer is being placed over the playing board and so that the game can be studied between playing sessions without removing the retainer.
Although the Go boards and stones used in tournaments and in most casual games are standardized in dimensions and in the number of vertical and horizontal lines (19 by 19), smaller boards (13 by 13 or 9 by 9) are often used in teaching beginning players, or to shorten the time required to play a game. It is unlikely that a game played on a board of reduced size would require more than one playing session, but retainers for such boards could be considered if there appeared to be a need for them.
When a game of Go is adjourned, to be completed later, there are certain items of information (in addition to the positions of the black and white stones on the board) which need to be retained. First, it is necessary to know whether it is the player with the black or the white stones whose turn it is to place the next stone. Second, there may be stones of either color, or both, which have been captured. It is not the absolute number of such stones but rather the excess of one color over the other which is significant. Thus, for example, if fifteen black and five white stones have been captured then a net count of ten black captured stores should be recorded. Third, there may be one particular intersection on the board on which the player whose turn it will be when the game is resumed is forbidden to place a stone, by reason of "ko"--a situation well known to Go players. Although these three items of information could be recorded on paper, a desirable feature for a Go retainer would be the incorporation of means for preserving this information--preferably in a way which does not add appreciably to the bulk of the retainer and which is easy to use but not obtrusive or displeasing in appearance.